JOINT TRANSFORM CORRELATOR SUBTRACTING A MODIFIED FOURIER SPECTRUM

The optically generated joint Fourier transform (JFT) of a test image and a reference image is processed using a new method: the JFT is reco rded twice. In the second recording the reference image is phase shift ed by a with respect to the first recording. The two JFT's are subtrac ted and binarized with a threshold of zero. Strong correlation peaks a re obtained, and correlations within the test image are suppressed. So me results of optical implementation are presented, using a ferroelect ric liquid crystal display with 128 x 128 pixels for data input. The p hase shift of the reference was implemented by the contrast-inverted r eference input on the binary light-modulating device. Processing of th e JFT is done by a CCD camera, a frame grabber, and a personal compute r. (C) 1995 Optical Society of America